Electro-assisted Biological Technology For Treatment Of Simulated Phenolic Wastewater

Electro-assisted biological technology(EABT)is a newly developed technology for wastewater treatment.Since it can enhance biological treatment and promote the biodegradation of refractory organics,it has been paid attention in the wastewater treatment field.However,in EABT,microbial form,biofilm carrier selection,and applied mode of electrical field still needs to be optimized.In view of the present insufficient in the stud ies of EABT,in this thesis,phenolic compounds were used as target contaminants,effect of applied electrical filed on different form of aerobic/ anaerobic microbes were investigated,bioelectrical reactors(BERs)packed with conductive carbon felts as biofilm carriers were constructed and applied mode of electrical field was optimized.On this basis,electro-assisted anaerobic-aerobic coupling biofilm reactor was constructed for phenol-containing wastewater and simulated phenolic wastewater treatment.The effect of direct current(DC)on the biodegradation of phenol by anaerobic/aerobic suspended biomass was investigated.Results showed that phenol biodegradation rate was inhibited with current ranged from 10 m A to 40 m A.This effect was caused by low p H values and low biomass.For attached anaerobic/aerobic biofilm,when carbon felts were used as biofilm carriers,phenol biodegradation was accelerated under an optimum DC of 2 m A in batch test,and the stimulation effect was consistent with the changes of ATP content.In the long-term operation,a high and stable phenol removal efficiency could be achieved with applied DC of 2 m A,especially with the intermittent DC applied mode,resulting in a phenol removal efficiency of over 97% and special microorganisms related with genera of Zoogloea and Desulfovibrio were distinctively enriched.Short-term and long term electrical stimulation have no effect on the anaerobic biodegradation of phenol,unless adding an electron acceptor into the cathode chamber,such as nitrate.Proposed electro-assisted anaerobic-aerobic coupling biofilm reactor with an HRT of 6 h and 9 h improved the removal efficiency of phenol,when the applied voltage was 1.2 V.Intermittent voltage application was better than continuous one,with high phenol removal efficiency with an HRT of 6 h.Functional microbes,such as Acinetobacter,Cloacibacterium,Acidovorax,Zoogloea,were enriched at long-term operation of electro-assisted anaerobic-aerobic coupling biofilm reactor.Electro-assisted anaerobic-aerobic coupling biofilm reactor was used to enhance the biological removal efficiency of the simulated phenolic wastewater.When a voltage of 1.2 V was supplied to the anaerobic-aerobic coupling biofilm reactor with an HRT of 9 h and 6 h,chemical oxygen demand and total phenolic removal efficiency was improved,and the biological removal efficiency of 4-nitrophenol,2,4-dinitrophenol and 2,4-dichlorophenol were 79.8%,80.2%(anaerobic stage used as anode chamber)and 100%(anaerobic stage used as cathode chamber),respectively,which was higher than that of the control reactor not exposed to voltage(26.0%,34.7% and 71.4%).Functional microbes,such as Rhodococcus,Achromobacter,Sphingobium,Sedimentibacter and PSB-M-3,were enriched at long-term operation of electro-assisted anaerobic-aerobic coupling biofilm reactor,which was benefical to enhance biodegradation of phenolic compounds.